Telomerase activity in breast cancer cells under treatment with crocin

Crocin is a major constituent of saffron, the dried stigmas of Crocus sativus L., which is used mainly as a herbal medicine or a food coloring agent around the world. Novel publications reporting a cancer preventive effect for crocin motivated us to evaluate telomerase activity, the main cause of immortality in cancer cells, under treatment with crocin. IC50 concentration of crocin was estimated in MCF-7 cell line, a breast adenocarcinoma cancer model, by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) test after 48 hours of treatment. A conventional telomere repeat amplification protocol (TRAP) assay and a real-time quantitative telomere repeat amplification protocol (qTRAP) assay were used to estimate relative telomerase activity in crocin-treated cells in comparison with untreated control cells. Telomerase activity in the treated cells with different concentrations of crocin up to IC50 showed an increment after administration of very low doses of crocin, whereas higher concentrations of crocin remarkably inhibited the enzyme in a dose-dependent manner. IC50 values of crocin reduced by 85% in comparison with untreated control cells. qTRAP estimations show a good correlation with the conventional assay results. Antiproliferative effect of crocin in cancer cells is probably due to strong inhibition of telomerase activity.